Memory mapped IOs:
All memory and IOs that are addressed using same memory map are called Memory mapped IOseg. Motorola
Port Mapped IOs:
Method in which, memory is mapped on one memory map, while IOs are mapped on different memory map is called Port mapped IOsSo here with same address, either IOregister / memory location can be accessed depending upon teh IORQ line value
So if any architecture says it has Port mapped IOs, then it should have a separate instruction for performing fetch from memory and fetch from IO.
NOTE: IORQ line is completely handled by CPU hardlogic after decodiong instruction. User code can't access it through some instruction call.
eg. Intel
http://www.bogotobogo.com/Embedded/memory_mapped_io_vs_port_mapped_isolated_io.php
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